Yes, I took the picture.
It's at a friends Antique business.
In a case, but normally when in service would have been hooked up, and mounted differently.
From another forum I'm on:
Spotted this the other day, and thought I'd share.
Thought we could start a new thread here of things we've seen that are out of the ordinary, post it up, and see if others know what it is.
At first I thought it was a large light bulb, as it's glass and shaped like a light bulb.
Except for the six glass protrusions around the bottom.
Looks really cool.
Is about 2 to 3 feet tall, and inside a case made of some sort of plastic.
The guy told me what it was, and I will share it later.
Just thought I'd see what some of you might think it is.
I looked up what he told me, and I did not see anything like it.
This guy is an antique hardware dealer, so this thing must be old.
Does it have a gas inside that becomes excited by a direct current field?
I'm not sure how it works, but you may be onto something.
I was told it was a selenium rectifier, and changed AC current to DC current.
They would be mounted in the hydro room/vault of a building.
Searches for a selenium rectifier didn't help much, but I did stumble onto what it is, a Mercury Arc Rectifier:
commons.wikimedia.org/wiki/File:Mercury_Arc_Rectifier.jpg
And another similar Rectifier:
diyaudioprojects.com/Gallery/displayimage.php?pid=470
www.google.ca/search?q=%22Mercury+Arc+Re...40WJTyAdq4jAOt6an4Aw
en.wikipedia.org/wiki/Mercury-arc_valve